The above colour and parallax criteria combined together returned an initial
sample of 29 514 GALAH stars. This sample could contain hotter giants of G
and K spectral types affected by a large reddening or cool giants of a
spectral type other than M (like the Carbon giants). To prune them out and
retain only those with an M-type spectrum, we looked for signatures of their
distinctive TiO absorption bands in the GALAH spectra. This may have
picked-up also some S-type giants whose spectra, in addition to TiO bands,
show also molecules involving \(s\) -type elements (ZrO in particular;
[1]}). Some percentage of known SySt do indeed
possess S-type giants [2]}.
